1. Field of the Invention
The present invention relates to a car AC generator having a cooling function with a cooling liquid and cooling air.
2. Description of the Prior Art
FIG. 3 is a sectional view of a brushless car AC generator disclosed by Japanese Patent No. 4-68850. In FIG. 3, reference numeral 101 denotes a generator case. A bowl-like front bracket 102, a bowl-like rear bracket 103 and a cylindrical enclosing member 104 are combined together to form an inner part chamber 105 and an outer first cooling chamber 106. Denoted by 107 is a sealing member such as an O ring fitted in an interface portion between the front bracket 102 and the rear bracket 103, 108 a gasket fitted in an interface portion between the front bracket 102 and the enclosing member 104, 109 a gasket fitted in an interface portion between the rear bracket 103 and the enclosing member 104, and 110 an inflow port formed in the rear bracket 103. Reference numeral 111 represents a cylindrical stator which comprises a stator magnetic pole 112 and a stator coil 113 and is installed in the enclosing member 104, and 114 is a generator shaft which is rotably placed in a center portion of the front bracket 102 and a center portion of the rear bracket 103 by a front bearing 115 and a rear bearing 116. Denoted by 117 is a pulley which is fitted onto the generator shaft 114 projecting forward from the front bracket 102 so that it can turn together with the shaft 114, 118 a rotary magnetic pole which comprises a first rotary magnetic pole 119 fitted onto the generator shaft 114 so that it can turn together with the shaft 114 and a second rotary magnetic pole 121 fixed to a peripheral portion of the first rotary magnetic pole 119 through a support ring 120 in the part chamber 105. Reference numeral 122 denotes an exciter which comprises an excitation pole 123 fixed to the rear bracket 103 and an excitation coil 124 attached to the excitation pole 123 and which is stored in a cylindrical container portion 125 formed in the rotary magnetic pole 118. An air gap is existent between the stator 111 and the rotary magnetic pole 118 and between the rotary magnetic pole 118 and the excitation pole 122. Denoted by 126 is a heat conductor, extending through the rear bracket 103, for radiating the heat of the exciter 122, 127 a sealing agent charged into a portion where the heat conductor 126 extends through the rear bracket 103, 128 a plate-like cooling cover which is placed upon the rear bracket 103 to form a second cooling chamber 129 between it and the rear surface of the rear bracket 103, 130 a connection passage formed in the rear bracket 103 which connects the first cooling chamber 106 and the second cooling chamber 129, 131 a gasket fitted in an interface portion between the rear bracket 103 and the cooling cover 128, 132 a voltage regulator installed on the rear surface of the cooling cover 128, 133 a voltage regulator terminal, 134 a rectifier installed on the rear surface of the cooling cover 128, 135 a rectifier terminal, 136 a stator terminal connected to the rectifier terminal 135 and projecting from the enclosing member 104, 137 an external terminal provided in the vicinity of the rectifier 134, 138 a connector for the external terminal 137 connected to the voltage regulator terminal 135, 140 a protective cover attached to the rear bracket 103 to cover the cooling cover 128, the voltage regulator 132, the voltage regulator terminal 133, the rectifier 134, the rectifier terminal 135, the stator terminal 136 and the connector 138, 141 a hole formed in the protective cover 140 for the external terminal 137 to project from the protective cover 140, and 142 a cooling liquid.
A description is first given of the power generation operation of the AC generator of the prior art when it is used in an automobile. The AC generator is installed outside the cylinder block of an engine, a ring-shaped belt is laid between a pulley provided on the crank shaft of the engine and the pulley 117 of the AC generator, and the external terminal 137 is wired to the battery of the automobile. When a driver turns on the ignition switch of the automobile in this state, a current runs from the battery of the automobile to an ignition coil to start the engine, an excitation current runs from the battery to the excitation coil 124 through the voltage regulator 132 at the same time, and the stator magnetic pole 112, the rotary magnetic pole 118 and the excitation pole 123 form a magnetic circuit. When the generator shaft 114 turns by the start of the engine and the rotary magnetic pole 118 turns, the first rotary magnetic pole 119 and the second rotary magnetic pole 121 pass by the stator magnetic pole 112 alternately, whereby an alternating magnetic flux runs through the stator coil 113 and 3-phase alternating induced electromotive force is generated in the stator coil 113. This induced electromotive force is adjusted by the voltage regulator 132, rectified by the rectifier 134 and charged into the battery from the external terminal 137 through an unshown wire.
A description is subsequently given of the cooling operation of the AC generator of the prior art when it is used in the automobile. The AC generator is attached to the engine, the inflow port 110 and an unshown outflow port are connected to an engine cooling system by an unshown pipe, the AC generator generates power by the start of the engine, and the water pump of the engine cooling system is driven to circulate the cooling liquid. In this state, the cooling liquid 142 shown by dotted lines flows from the inflow port 110 to the first cooling chamber 106, the connection passage 130 and the second cooling chamber 129 as shown by an arrow X3. In the first cooling chamber 106 and the second cooling chamber 129, heat generated from such parts as the stator 111, the exciter 122, the voltage regulator 132 and the rectifier 134 by the operation of power generation is absorbed by the cooling liquid 142 through heat exchange with the cooling liquid 142. The cooling liquid 142 which has absorbed the heat returns to the engine cooling system from the outflow port (a structure similar to this cooling system is disclosed by FIG. 12 of Japanese Laid-open Patent Application No. 8-130854).